1. Field of the Invention
This invention relates to a card-like optical information recording medium and an apparatus for recording and/or reproducing information on such medium.
2. Related Background Art
Various forms such as a card-like form, a disklike form and a tape-like form are known as the forms of a recording medium used to record information thereon by the use of a light beam and reproduce the thus recorded information by the use of a light beam. Above all, an optical information recording medium formed in a card-like shape (hereinafter referred to as the "optical card") is expected to create a big demand as a recording medium which is easy to manufacture and excellent in portability and accessibility.
A popular example of such optical card is shown in FIG. 1 of the accompanying drawings.
In FIG. 1, reference numeral 41 designates a rectangular optical card base body formed of a flexible material such as a plastic sheet. The base body 41 is provided with a recording area 42 in which a plurality of parallel information tracks 43 are recorded along the longer sides of the base body 41.
FIG. 2 of the accompanying drawings is a partly cut-away perspective view showing an example of an apparatus for effecting recording of information on the optical card as described above and/or reproducing card (an information recording-reproducing apparatus for optical cards).
In FIG. 2, reference numeral 52 denotes a frame to which is fixed a first drive motor 54. A pulley 56 is mounted on the rotary shaft of the motor 54, and a pulley 58 forming a pair with the pulley 56 is rotatably mounted in the frame 52. A belt 60 is passed over these two pulleys 56 and 58 and is movable in the direction of arrow A--A. An optical card conveying carriage (shuttle) 62 is connected to the moving portion of the belt 60. The shuttle 62 can horizontally hold the optical card as shown in FIG. 1, and is formed with a window 62a in the upper portion thereof so that the recording area 42 may be exposed at that time, and is also provided with an entrance and exit 62b for the optical card at one end thereof.
A second drive motor 66 is fixed to the frame 52. Two guide rails 68 and 69 are also fixed to the frame 52 along the direction of arrow B--B, and a optical head 70 is mounted for sliding movement relative to the guide rails. The rotary shaft of the second drive motor 66 extends in the direction of arrow B--B and is screw-coupled to the optical head 70.
The optical card 64 may be inserted into the shuttle 62 in the direction of arrow A--A through the entrance and exit 62b, and this insertion is done such that the information tracks 43 on the optical card 64 coincide with the direction of arrow A--A. The second drive motor 66 is then driven to move the optical head 70 in the direction of arrow B--B to a position corresponding a desired information track 43, and then the first drive motor 54 is driven to move the belt 60 and move the shuttle 62 in the direction of arrow A--A, thereby recording information on the desired information track 43 by means of the optical head 70 or reproducing or erasing the recorded information on that information track.
The constructions and operations of the optical card and the recording-reproducing apparatus for such optical card according to the prior art have been described above, but in such optical card and apparatus, the information tracks 46 are formed as parallel straight lines as shown in FIG. 1 and therefore, during the recording, reproduction or erasing of information, it is necessary to reciprocally move the optical card 64 in the direction of the information tracks 43 relative to the optical head 70.
For this reason, during the reversal of the reciprocal movement of the optical card, a considerably great force required for deceleration, stoppage and acceleration acts and therefore, mechanical vibrations occur to the apparatus, and this has led to a problem that the proper conditions of focusing and tracking for accurately keeping the relative positional relation between the optical head 70 and the optical card 64 are disturbed and accurate recording and/or reproducing operation becomes difficult.
Also, during the reversal of the reciprocal movement, the relative speed of the optical head 70 and the optical card 64 varies remarkably and therefore, recording, reproduction and erasing of information are not effected. Accordingly, the other loss time than the time during which the recording, reproduction and erasing of information are actually effected becomes considerably great, and this has led to a problem that good working efficiency cannot be obtained.